In existing Intelligent Transportation Systems (ITS), an ad hoc peer-to-peer distribution network is created using low power transmitters and receivers in vehicles. Co-operative ITS (C-ITS) applications make use of an ad-hoc broadcast messaging network that is created by a collection of vehicles each of which has C-ITS applications broadcasting information to the nearby vehicles. The messages exchanged can provide information about a vehicle's location, bearing and speed, or they can contain alert information related to road conditions or sudden events such as unexpected braking, component failures etc. These ad hoc networks provide information to nearby vehicles, which in turn can relay the information to other nearby vehicles, but only vehicle generated data is transmitted, and the transmitted data cannot be received if other vehicles are not within range.
There has been focus on the creation of an infrastructure based network to overlay the ad hoc network. The infrastructure based network makes use of bridge points that are part of both the infrastructure network and the ad hoc network. These bridge points allow a subset of the messages relayed on the ad hoc network to be re-transmitted into the infrastructure based network. The infrastructure based network can then make use of a large number of data points and more powerful computing platforms to derive additional information and to provide additional services. The resulting messages can then be sent back to the bridge points and relayed across the ad hoc network.
When interacting with the infrastructure based network, a geomessaging client (also referred to as a geoclient) will be served by a first geomessaging server that is responsible for a first geographic region. When the geomessaging client moves out of the region served by the first geomessaging server, it will have to connect to a second geomessaging server serving the new location where the GeoClient has moved to. At present, infrastructure based networks, are envisioned as being based on either conventional Internet Protocol (IP) based networks, or based on IP Multimedia Subsystem (IMS) based networks. As a particular vehicle may be required to interact with at least one of the two systems, it is preferable that the architecture of the infrastructure based network will support the same vehicle based client regardless of whether the network is IP or IMS based. Furthermore, it may be advantageous if infrastructure nodes perform the same function regardless of the signaling technology employed and do so transparently to the geoclient.
At present, no such system has been developed or deployed. However, it is recognized that there are other networks with mobile nodes that move from one service area to another.
One skilled in the art will appreciate that mobile devices in a cellular network are subject to handovers between network service providers. In this process, a mobile device (e.g. a telephone handset) is served by a first network provider. When it moves outside the service area of the first network provider it loses service and thus determines that it is no longer in a service area of a first network provider. The handset can then perform a scan to build a list of available service providers. From this list, a new service provider is selected (typically by selecting a network provider on the list of available service providers that is also in a list of service providers with whom the first network provider has roaming agreements.) At this point, the handset begins the registration process with the second network. In some cases an active call may be maintained during this handover, but in many cases a hard hand over is required and the call is dropped. In either situation, the handset is an integral part of the process of selecting a new service provider. Additionally, the first network provider is not notified of the departure of the device, and instead only determines that the device is not active when it is no longer reachable by a network paging function. Such a handover system is not feasible for an ITS system. It is preferable that the user be able to be seamlessly transitioned between service providers when a boundary is reached.
Therefore, it would be desirable to provide a system and method that obviate or mitigate the above described problems.